Polishing machine for turbine blades



Feb. 27, 1951 E. DACKOR ETAL 2,543,235

POLISHING MACHINE FOR TURBINE BLADES Filed Dec. 29, 1948 10 Sheets-Sheet l 5y MQMHMHE Feb. 27, 1951 E. DAcKoR ETAL 2,543,236

PoLIsHING MACHINE FOR TURBINE BLADES Filed Deo. 29, 1948 10 Sheets-Sheet 2 fzz Veni. Drs Enga/' Dac'wz' E Nejboecl Feb.. 27, 1951 E. DAcKoR ETAL 2,543,236

POLISHING MACHINE FOR TURBINE BLADES Filed Deo. 29, 194s 1o sheets-sheer s Feb. 27, 1951 E. DACKOR ETAL 2,543,236

POLISHING MACHINE FOR TURBINE BLADES Filed Dec. 29, 1948 l0 Sheets-Sheet 4 35 J, Z/MEL/gg Feb. 27, 1951 E. DAcKoR ETAL PoLIsHING MACHINE FOR- TURBINE BLADES 10 Sheets-Sheet 5 Filed Dec. 29, 1948 Feb. 27, 1951 E. DAcKoR Erm. 2,543,236

POLISHING MACHINE FOR TURBINE BLADES Filed Deo. 29, 1948 1o sheets-Sheet 6 Ey JZQq//M mi? Feb. 27, 1951 E. DAcKoR Erm. 2,543,236

POLISHING MACHINE FOR TURBINE BLADES Filed Dec. 29, 1948 10 Sheets-Sheet 'T E5 Huf/'5 Feb. 27, 1951 E. DAcKoR Erm. 2,543,235

PoLIsHING MACHINE FOR TURBINE BLADES Feb. 27, 1951 E. DAcKoR ETAL POLISHING MACHINE FOR TURBINE BLADES 10 Sheets-Sheet 9 Filed Dec. 29, 1948 IIWWHE Feb. 27, 1951 E. DACKOR ETAL 2,543,236

POLISHINC- MACHINE FOR TURBINE BLADES Filed Deo. 29, 1948 l0 Sheets-Sheet lO It `l l?) *w Y n m Q *WM m -g Eff? l -s` w Q g g V s E5, @mZ/M o Patented Feb. 27, 1951 POLISHING MACHINE FOR TURBINE BLADES Emil Dackor and Edgar F. Nelboeck, Cleveland,

Ohio, and Otto Thiel, Detroit, toThompson Products, Inc.,

corporation of Ohio Mich., assignors Cleveland, Ohio, a

Application December 29. 1948, Serial No. 67,942 25 Claims. (Cl. 51-64) This invention relates to a polishing machine,

and particularly to a machine for rapidly and` economically eifecting the polishing of complex arcuate surfaces on a workpiece, such as the surfaces of a turbine blade.

It will be recognized by those skilled in the art that the surfaces of the blades of turbine wheels are of relatively complex configuration, for the most part having in cross-sectional contour an arcuate configuration wherein the radius of curvature of successive portions on the contour varies substantially. Heretofore, the quantity production of turbine blades has been substantially impaired by virtue of the fact that the polishing of the blade surfaces could only be satisfactorily accomplished manually. Such manual operation not only greatly increases the time and cost of production but has the further disadvantage of being dependant in a large extent upon the skill of the particular operator, and hence being subject to wide variations in the quality and uniformity of surface finish obtained.

According to the features of the present invention, a plurality of polishing units are mounted on a rotatable turret for movement in a horizontal plane toward and away from an operators station.

On each polishing unit a blade is positioned in a clamp-like workholder which engages the base of the blade, holding the body of 'the blade between opposed spring pressed pads over which abrasive polishing belts are trained. As each polishing unit is moved in a circular path on the I turret, the blade is reciprocated by power means carried by each unit in a substantially vertical direction between the pads and the pads are given a reciprocating movement in a substantially horizontal direction by means of a power driven linkage. Thus, during the polishing of the blade no definite polishing path is followed and as a result a highly polished, scratch free surface is obtained on the blade.

As each polishing unit approaches the operators station, a cam trip mechanism operates on the spring pressed pads to retract them away from the blade. This mechanism also is effective to index the abrasive belt to present a new polishing surface to the next blade to be polished and to also release the grip of the workholding clamp on the blade so that the operatorv can quickly and easily remove the polished blade and insert a new unpolished blade in the clamp. The operation of retracting the spring pressed pads, indexing the abrasive belt, and releasing the grip of the workholding clamp are effected 2 through a single power shaft and therefore the sequence of operations may be closely controlled. Accordingly, it is an object of this invention to provide an automatic polishing machine of the turret type wherein a plurality of polishing units receive articles at anoperator's station, polish them during continued rotation of the turret and return the polished article to the station for removal therefrom after a predetermined polishing time period whereby a single operator can easily consecutively load and unload all of the units.

It is a further object of this invention to provide an improved machine'for polishing complex arcuate surfaces of a workpiece, and particularly a machine that will rapidly, economically and uniformly effect the polishing of the blade surfaces of a turbine wheel.

Another object of this invention is to provide a polishing machine wherein a workpiece is reciprocated between abrasive belts disposed over spring pressed jaws and wherein the jaws are reciprocated simultaneously vwith the workpiece reciprocation in/a direction substantially normal to the path of'travel of said workpiece, the combined movement being effective to impart a highly polished surface to the workpiece which is free from yscratches typical of a uni-directional polishing movement.

A further object of the present invention is to provide improved means for indexing the to each consecutiveblade.

Another and still further object of the present invention is to provide means for automatically clamping and releasing a workpiece from a work abrasive belt for presenting a newwork surface v holder.

A still further object of the vpresentinvention is to provide an improved mechanism for syn-l chronizing the indexing of the abrasive belt with the release of the workpiece` from the workholder. f l,

Another and still further object of thisy invention is to provide a novel means for imparting a reciprocating movement to the belt-carry n ing pad of the polishing machine of the present invention.

Figure 1 is a more or less diagrammatic top plan view of the turret mounted polishing unit of the present invention;

Figure 2 is a fragmentary vertical sectional '-:iew taken substantially on line II-II of Figure 1;

Figure 3 is a fragmentary side elevational view of a polishing unit taken at line III-III of Figure l;

Figure 4 is a front elevational view of a polishing unit constructed according to the teachings of the present invention.

Figure 5 is a bottom plan view of the polishing unit of the present invention taken along the line V--V f Figure 4;

Figure 6 is a horizontal sectional view taken substantially on line VI-VI of Figure 4;

Figure 1 is a horizontal sectional view taken on line VII-VII of Figure 4 looking in the direction indicated by the arrows;

Figure 8 is a fragmentary side elevational view taken on line VIII-VIII of Figure Figure 9 is a fragmentary vertical sectional view taken on line IX-IX of Figure 4;

Figure 10 is a fragmentary vertical sectional view taken on substantially line X-X of Figure 3;

Figure l1 is a fragmentary horizontal sectional view taken on line XI--XI of Figure 8;

Figure 12 is a fragmentary vertical sectional view taken on line XII- XII of Figure 7;

Figure 13 is a fragmentary vertical sectional view taken on line XIII--XIII of Figure 4;

Figure 14 is a fragmentary vertical sectional view taken on line XIV-XIV of Figure 13;

Figure 15 is a fragmentary vertical sectional view taken on line XV-XV of Figure 3;

Figure 16 is a fragmentary vertical sectional view similar to Figure 15 showing a revolved position of the clamp of the present invention.

As shown on the drawings:

As seen in Figures 1 and 2, the reference numeral In indicates a circular table which is keyed to a short shaftI II rotatably supported on a pedestal I2 and arranged to be driven through a reduction unit I3 by a motor I4 which is mounted on the inner wall of a cylindrical support base I5. On the under side of the table I0 near its outer periphery a plurality of rollers I1 are mounted in any suitable manner for rolling engagement in a recessed track I8 provided in the upper surface of the cylindrical base I5. The rollers prevent binding of the table on the support base during operation of the table.

According to the teachings of this invention a plurality of polishing units 2B are rigidly secured in an upright position on the upper surface of the table ID by any suitable means. As the table is rotated by the motor I4 each unit consecutively passes an operators station where polished work units are removed from the unit and unpolished articles are inserted therein for subsequent polishing as the turret continues its rotation.

Ea-h polishing unit may suitably be mounted on an upright support plate 22 (Figure 2), which has a foot portion 23 secured to the table top, as by means of a plurality of bolts 24. The unit itself may be secured to the upright member 22 by any suitable means as by bolting.

GENERAL OPERATION or THE PoLIsHING MACHINE In Figures 3 and 4 the reference numeral 24 indicates generally the supporting base of a polishing unit which base is secured to the upright support member 22 having an outwardly extending central pad 25 on which a workholding carriage 26 is disposed for sliding movement in a vertical direction longitudinally of the polishing machine. The carriage 26 is reciprocated by means of a power driven mechanism 28 which is mounted on an elevated pad 29 at the upper end of the support face. A turbine blade B is gripped in a clamping assembly 30 at the lower end of the carriage 26 and extends between rubber pads 32 (Figure 4), over which abrasive polishing belts 34 are trained, as shown in Figure 5. The path of travel and the mechanism for feeding the belts over the pads will be described in detail hereinafter.

As best seen in Figures 3 and 11 a lever mechanism 35, connected to a pad holder 33 is provided to reciprocate each pad in a substantially horizontal direction as the blade B is reciprocated vertically between the abrasive belts 34 disposed over the pads. A pad retracting mechanism 36, Figures 3 and 5, is pivotally connected to each pad assembly and is arranged to simultaneously separate the pads to permit a new blade to be positioned between the belts and to permit new polishing surfaces of the belt to be indexed into position over the pads. This retracting mechanism is driven by a shaft 31 (Figure 5), journaled in the base 24.

As seen in Figures 2 and 9, the shaft 31 is driven through gears 38 and 39 from a shaft 40 which is journaled in the support member 22 and has, at its lower end, a cam follower arm 4I (Figure l) which is periodically tripped by a camming surface 42 on the interior wall of the support casing I5. It will be understood of course that the cam is so designed as to have a dwell portion of sufficient length to allow the operator to insert the new blade into position in the clamp before the cam follower rises off the camming surface.

Indexing of the abrasive belt 34 is accomplished through the shaft 31 which is connected through a linkage 43 (Figure 9), to a ratchet mechanism 44, which periodically rotates a shaft 45.

The jaws of the clamp 38 are automatically opened by means of a bar 46 which is actuated by a linkage 43 attached to the shaft 45.

DRIVE MECHANISM ron THE WORK CARRIAGE In Figures 3, 4, 13 and 14, the reference numeral 41 indicates a gear housing which is secured to the pad 29 of the base 24 by a plurality of bolts 41a. A shaft 48 (Figure 14), is journaled in the gear housing 41 in bearing assemblies 49. A pulley 5D, keyed to one end of the shaft 48, is driven through a belt 5I from an external source of power. At the other end of the shaft, a pinion gear 53 is secured thereon in mesh with a crank gear 54 which is keyed to a shaft 55 journaled in bearings 56 of the gear housing. A crank way 51 is secured by bolts 58 (Figure 13), to the large gear 54. The crank way 51 has upstanding walls 59 and 6U defining a passage in which the threaded shank 6I of a crank spindle G2 is enclosed. At one end, the spindle B2 has opposed shoulders 63 and 64 abutting opposite sides of a spacer block 6B which is held against the crank way 51 by a retainer plate 51. A plurality of bolts E8 secure the retainer plate 61 to the crank way 51. A crank pin 10 (Figure 14), is provided with a sleeve portion 1I threaded on the spindle 62. A bearing 12, fitting over the crank pin 10 receives one end 13 of a connecting rod 14 which is held thereon by a nut 15 and washer 15.

Thus, when the power driven shaft 48 is rotated, the gear 54 and the attached crankway 51 will be rotated about the axis of the shaft 55 causing the crank pin 10 to rotate about the same axis.

The amount of eccentricity of the crank pin 10 auaaae and consequently the length of the reciprocating stroke of the blade carriage can be adjusted by rotating the spindle 62 to move the sleeve portion 1| on the crank pin 10 toward or away from the axis of the shaft 55.

The connecting rod 14 has a lower eye end at 18 (Figures 3 and 4), journaled on a bearing portion of a cross head 19 which extends through an opening 80 in the carriage 26. A spindle 6| threadingly engages the cross head 19 and transmits the reciprocating movement of the connecting rod 14 through shoulders 83 and 84 to the carriage. By threading the spindle 6| into or out of the cross head 19 the beginning and end of the polishing position can be adjusted.

The carriage 26 has flanges 86 and 81 (Figures 4 and 6), which are arranged to slide in passages defined by wall portions 88 and 88a of the base 24 and elongated plates 89, which are secured to the base 24. Thus, the carriage 26, actuated by the connecting rod 14, must follow a reciprocating, guided path along the base 24.

WORK CLAMPING MEcHANIsM The blade B which is to be polished is held between arms 92a and 92h of a chuck 92, Figures and 16, which is journaled on bearings 93 and 94 in the opened forward end of the carriage 26. A bearing retainer ring 96 is secured to the lend of the carriage by screws 91'. A sleeve 98 is threaded on the end of the chuck pressing a lock washer 99 against the end of the bearing 93. A pin |00 is slidably disposed in the chuck 92 having a tapered forward end |0| and a threaded rear end |02. A spring |03 disposed in said sleeve 98 is bottomed against a washer |05 which abuts a shoulder |06 on the pin |00 and is pressed there against by a cap |08 which is threaded on the sleeve 98. Thus, the pin |00 is spring pressed forward so that the tapered end |0| is wedged into a hole |09 defined by recesses ||0 at the rear portion of the two jaws ||2 which are pivotally mounted on pins ||3 between the forward arms 92a and 92h of the chuck 92. Each jaw has a recess portion 4 near its forward end into which a root portion B of the blade B is disposed. As the tapered end of the pin "|00 is spring urged into the hole |09, the jaws ||2 pivot on the pins ||3 and clamp the workpiece B in position. In Figure 15 the work clamping assembly is shown in a clamping position with the rod |00 moved between the clamping jaws to pivot the jaws against the workpiece in clamping relation thereon. In Figure 16 the retracted open position of the clamping assembly is illustrated.

A spring I6 is disposed in recesses in the jaws ||2 forurging the forward end of the jaws to open position.

MOUNTING Fon THE ABRASIVE BELT Ihe abrasive belt 34 is unwound from a supply spool ||1 (Figures 4 and 10), rotatably journaled on a mandrel ||8 which is secured by cap screws ||8a and ||9 to an oscillatable arm |20. The arm |20 is rotatably held on a pin |2| extending outwardly from the frame structure 24 by a screw |2|a. The arm |20 is normally urged counterclockwise by a spring |22 which engages the arm |20 in hooked engagement at one end and is anchored to the frame at the other end as at |23. The spool ||1 is held on the mandrel ||8 by a retainer ring |25 at a spring loaded adjusting screw |26. The mandrel I8 is also provided with a collapsing sleeve |29 on which the abrasive belt is wound after it has been used.

As best seen in Figures 3 and 5, the belt 84 on each side of the machine travels along identical paths over identical guide rollers. A description of the belt on one side only will therefore be sufficient for an understanding of this feature of the invention.

After leaving the supply spool Ill, the belt 34 is directed downwardly over a guide post or roller |30 where the direction of travel of the belt is changed and it is directed forwardly over the guide roller |3| which is journaled between the posts |32 of an end plate |33. As seen in Figure 5, the belt then proceeds in a substantially horizontal direction over spaced guide rollers |36 and |31 between which is located the pad 32. From the roller |31 the belt ls trained over a guide |38 mounted between posts |40 which are mounted at the rear of the machine on the inner face of the end plate |33. After passing over the roller |40 the belt is directed forwardly to a guide roller |42 which directs it upwardly around a friction speed roller |43 (Figure 3) ,l which has a surface covered with a material of high frictional characteristics such as rubber. From the-roller |43, the tape is wound on the collapsible sleeve |29 of the mandrel IIB.

It will of course lbe understood that as the frictional roller |43 is oscillated by a ratchet mechanism, to be described in detail hereinafter, itwill carry the tape along with it and wind it on the collapsible sleeve 29 with which it is in frictional engagement.

MOUNTING AND'OPERATION oF THE TAPE CARRYING PAD In Figure 5 a view of the polishing machine is shown as seen looking upwardly at the bottom thereof. It will be noted that the linkages 36 which are effective to retract the belt engaging pads 32 are identical on both sides of the machine and are .driven from a common shaft 31. It is therefore believed that a detailed description of the operation and structure of the pad controlling mechanism on one side of themachine will be sufficient to disclose this feature of the invention.

Pad mounting The reference numeral |33 indicates a flat end frame member having an aperture |34 (Figure 7), in which an annular hub member |36 with an aperture |31 is disposed. A bracket |38 has a flange |39 and a sleeve portion |40 and is held between the hub |36 and a retainer hub |4| by an upper spacer bar I 42 and a lower spacer bar |43 which have threaded ends receiving nuts |44 and washers |45. The sleeve portion |40 of the bracket |38 thus defines a cylindrical housing into which a bearing sleeve |41 is inserted. A cross slide |49 has a cylindrical outer surface and is arranged for sliding movement in the sleeve |41. The sleeve |41 has three spaced longitudinal apertures |50, |5| and |52 disposed on the horizontal center line of the slide |49. One end of the apertures |50 and |5| is internally threaded to receive the threaded end of the plugs |54. Guide rods |55 are slidably disposed in the other end of the apertures |50 and |5| with reduced portions |56 of the rods passing through reduced portions of the apertures. Shoulder portions are therefore provided in the slide |49 which limits the outward movement of the rod |55. Springs |58 are .disposed between the plugs |54 and the rods |55 in recesses provided in the opposed ends of these members.

A pad holder 33 has an H-shape, as seen in Figof the base 24 (Figure 3).

direction outwardly of the housing towards a pad 32 which is disposed in the housing |40 on the opposite side of the machine. As seen in Figure 5,

th'e downwardly extending flange portion |39 of the bracket |38 is bolted to an upstanding wall |65 of the base 24 for supporting the entire pad housing and mechanism.

It will be seen in Figure 4 that a plurality of set screws |61 are threaded through the sleeve portion |40 of the bracket |38 for engaging the bearing sleeve |41 (Figure '7) and lreventing relative rotation of these two members. Further, as seen in Figure 3, a substantially rectangular key |59, which is co-extensive longitudinally with the cross slide |49, fits in a recessed portion of the cross slide |49 and in a recessed portion |1| of the bearing sleeve |41 to prevent relative rotation of the bearing sleeve |41 and the cross slide |49.

Mechanism for retreating the pads The pad 32 may be retracted by means of a lever |12 (Figure 7), of the linkage 36 which is pivotally mounted by a pin |13 on a bracket |14 secured, by bolts |15, to the upstanding wall |66 One end |12a of the lever |12 is pivotally connected to a rod |11 which is pivoted on a link |18 (Figure 5), keyed to the shaft 31. The rod |11 may suitably have an internally threaded end portion into which the threaded end of a pivoting connector |80 is engaged.

The other end |12b (Figure 1), of the lever |12 is pivotally secured by a pin |8| between a pair of arms |82a of an H-shaped link |82 (Figure 12). A connector |84 is secured by a bolt |85 in the longitudinal aperture |52 of the cross slide |49, having one end pivotally disposed between the other pair of arms |82b of the H-shaped link |82 on a pin |81. As the lever |12 is pivoted on the pin |13, the cross slide |49, and consequently the pad 32, slide bodily back and forth in the bearing sleeve |41, on Figure 7.

Reciprocation of the pad In Figures 3 and 4, it is seen that the linkage includes a shaft |90 which extends across the machine and is journaled in bearing arms |9| secured to the upstanding walls |66 of the base 24. At one end |92 of the shaft |90 a bellcrank |93 is keyed. The bellcrank has an arm 93a (Figure 3), extending substantially downwardly for pivotal connection to a connector |95 into which is threaded an elongated connecting rod |96. The rod |96 is given a reciprocating movement by means of a drive mechanism |91 (Figure 4).

In Figures 4 and 14, it is seen that the drive mechanism |91 includes a pulley |98 connected by a belt |99 to a drive pulley 280 that is keyed to the shaft 55. The driven pulley |98 is keyed to a shaft 202 for rotation in a speed reducer assembly 203 which is mounted on a bracket 204 secured to the frame of the machine.

The shaft 202 has an enlarged end portion 202a, (Figure 6), in which a transverse groove 202b is provided. One end 205 of a connector 208 is slidably disposed in the groove 202a while the other end 201 receives the bearing end of the connecting rod |96. A screw 208 is threaded through a plate 208 secured to the enlarged end 2020. and into the connector end 205 permitting adjustment of the connector transversely of the shaft 202 to vary the eccentricity of the connecting rod end as it rotates about the axis of the shaft 202. Thus the stroke of the connecting rod |96 may -be adjusted.

The other end |93b of the bellcrank |83 is blfurcated and is pivotally mounted on a pin 2| to a composite link 2|2 (Figure 1l), comprising a plurality of straps secured together by bolts. A connector head 2|4, is pivotally mounted at the upper end of the link 2 2 and has an arm threadingly engaged in a lever 2|5 which is disposed in a longitudinal slot 2|6, which extends through the cross slide |49. vThe lever 2|5 is pivoted near its middle portion on the pin which secures the retracting mechanism to the cross slide |49 and is pivotally connected at its free end to the pad holder 32 by a pin 2 |1. It will be seen in Figure 11, that the slot |50 in the pad holder 33 permits the pad holder to be moved in a vertical reciprocating movement without affecting the pins |59 mounted on the forward end of the mechanism used to retract the pad.

In Figure 4, a lever 2|9 is illustrated as keyed to the end of the shaft on the side of the machine opposite to the driving side. This lever is effective to reciprocate the pad 32 on that side of the machine in exactly the same manner as described in connection with the lever |93.

rIherefore, as the shaft |90 is oscillated by reciprocation of the connecting rod |95, the levers |93 and 2|9 continuously move the pad holder 33 in a substantially horizontal reciprocating path. As heretofore mentioned, this horizontal reciproeation movement of the pad takes place as the workpiece B is reciprocated in a substantial vertical direction between the abrasive belts disposed over the pad 32.

RELEASE MEcHANIsM ron rm: WoniHoLnrNc Crm The shaft 40 which is periodically oscillated by the cam on the interior wall of the base |5 drives a shaft 31 which passes through and is keyed to two levers 22| and 222 (Figure 9), each of which has a bifurcated end portion. The lever 22| is pivotally connected to one end of the linkage 43, which carries at its opposite end a connector head 224 (Figure 4). The head 224 is pivotally mounted between arms 225 of a lever 226 which has an H-shaped contour in a plan view, as shown in Figure 4. However, the arms 225 and 221 of the lever 225 are disposed at an angle to each other as seen in Figure 9. 'Ihe lever 226 is freely mounted on the shaft 45. A strap or barV 46 is pivotally connected between the arms 221 of the lever 226 and between the bifurcated end 229 of a lever 230 which is pivotally mounted on a shaft 23| journaled in the support base pad 25 (Figure 3).

When the shaft 31 is rotated in one direction, the link 43 will pivot the lever 226 counterclockwise as seen in Figure 3 causing the bar 46 to move bodily forwardly into contact with a roller 232. The roller 232 is pivotally secured to a crank arm 233 (Figures 15 and 16) that is keyed to a shaft 234. 'I'he shaft 234 is journaled in a bracket 235 secured to the carriage 26 by cap screws 233. At its inner end the shaft 234 carries an arm 231 mounted at the peripheral portion of a circular end member 236 and extending away therefrom for contact with a pair of adjustable nuts 240 on the threaded end of the pin |00. As the roller 232 is swung outwardly by the bar 46, the arm 231 will contact the nuts and move them longitudinally in the carriage as seen in Figure 16 thus retracting the forward end of the pin |00 from between the jaws 2 of the clamp. A pin 242 secured to the carriage 26 limits the clockwise rotation of the crank 233 (Figure 3).

Thus the pin which is normally spring urged into engagement with the jaws of the clamp, is automatically retracted when the bar 46 is raised due to rotation of the shaft 31.

As seen in Figure 6, a rod 242, journaled in a bearing 245 secured to the base 24 has an end portion pivotally mounted in the bifurcated end of the lever 222. The rod 244 is threaded at one end to receive a nut 241 which-provides an adjustable stop for a washer 248 freely disposed on the rod 244. A spring 249 disposed over the rod 244 between the washer 248 and the bearing 245 urges the rod to the left, as seen in Figure 6, and causes the shaft 31 to rotate clockwise pivoting the lever 22| clockwise. The link 43 is thus moved to pivot the lH-shaped lever 226 clockwise as seen in Figure 9, with the result that the bar 46 is moved away from the handle 232 ofthe clamp release mechanism. Therefore, after the jaws of the clamp have been released by the action of the bar 46, the spring-urged rod 244 will cause the bar to be moved downwardly. This action of the rod 244 will of course be opposed by the action of the camming surface 42 on the interior wall of the casing |5. Therefore, the jaws of the clamp will be opened when the follower arm 4| is on the dwell portion of the camming surface 42 and the jaw will be spring urgedA to a closed position by spring |03 (Figure 15), at all other times.

The belt 34 is indexed to present a new polishing surface to the next blade to be polished by means of a ratchet Wheel 250, Figure 9, which is mounted on the shaft 45. A pawl 25|, pivotally mounted on an ear 252 of the lever 226 by a pin 253, engages the ratchet wheel 250 each time the linkage 43 is moved to the right, as seen in Figure 9, by the lever 22|. The take-up friction roller or spool |43 (Figure 10) is keyed to the shaft 45 and thus is indexed each time the ratchet wheel 250 is actuated.

From the foregoing description it will be seen that there is provided in this invention `a novel automatic polishing machine of the turret type wherein a plurality of polishing units are mounted on a rotatable table in spaced relation and are arranged to have a workpiece inserted in a clamp member as the unit passes the operators station and to polish the workpiece as the table rotates through substantially 360. A novel mechanism is provided for reciprocating the workpiece between spring-pressed pads over which is disposed an abrasive belt. The pads and the belt in turn are given a reciprocating movement in a direction substantially normal to the direction of reciprocation of the workpiece, whereby a scratch-free polished surface is attained on the workpiece. A novel automatically operated mechanism is also provided for operating on each polishing unit as it approaches the operators station to perform the threefold operation of releasing the grip of the work-holding clamp, retracting the springpressed pads from around the workpiece, and inl0 dexing the abrasive belt to a new unused working position.

'I'his machine is very elcient in operation and eliminates a great amount of hand polishing, with resultant savings in production costs.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitat d by the scope of the appended claims.

We claim as our invention:

1'. A polishing machine comprising a rotatable table, a plurality of polishing units mounted on the table for rotation therewith, work-carrying means on each unit, opposed polishing members on each unit for receiving the work therebetween, drive means for shifting the work carrying means relative to the polishing members to cause polishing of the work by the polishing members, means for rotating said table to carry the umts toward and away from an operators station, and mechamsml acting 4on the units as they approach the operators station to release the work carrying means and separate the opposed polishing members for easy removal of the work from the successive units.

2. A polishing machine comprising a rotatable table, a plurality of polishing units mounted in spaced relation on the periphery of said table, a cam mounted below said table at an operators station,'means for rotating said table to move each unit past the operators station, spaced polishingmeans on each of said units including a pair.' of abrasive belts stretched between supply spools and take-up spools, clamping means having jaw` members holding a work piece between said abrasive belts, means for reciprocating said clamping means, spring-pressed pads urging said abrasive belts against said work piece, a lever connected to each pad for retracting the pad from contact with the associated abrasive belts, a ratchet mechanism connected to said abrasive belts for indexing the belts over said pads, a bar operable on said clamping means to release their jaws, a rock shaft journaled in each polishing unit having connection with said pad retracting lever, with said ratchet mechanism and with said' jaw releasing bar, and a cam follower on each rock shaft arranged to be actuated by said cam for oscillating said rockmshaft to retract the pads, index the abrasive belts and release the clamp jaws as the polishing unit reaches the operators station.

3. A polishing machine comprising a base, a table rotatable relative to said base, a .cam disposed on said base at an operators station, a plurality of polishing units mounted in spaced relation around the periphery of said table, means for rotating said table to move each unit 'past the operators station, abrasive belts mounted on each of said units in spaced relation, clamping means f having jaw members holding a workpiece between said abrasive belts, means for reciprocating said clamping means, spring pressed pads urging said abrasive belts against said workpiece, a rock shaft journaled in said units and connected to said clamping means for releasing jawmembers connected to said pads for retracting the pads from contact with said abrasive belts, and a cam follower in driving engagement with said shaft and arranged to be actuated by said cam for releasing the jaws of said clamps and retracting said pads at the operators station.

4. A polishing machine comprising a rotatable table, a plurality of polishing units mounted in spaced relation around the periphery of said table, means for rotating said table for moving each unit past an operators station, clamp means on each unit for holding a workpiece, abrasive means on each unit operable on the workpiece for polishing the same, spring urged pads on either side of said abrasive means pressing said abrasive means against said workpiece, means for reciprocating the workpiece between said pads, and means for reciprocating said pads substantially normal to the direction of reciprocation of said Work piece.

5. A polishing machine comprising a rotatable table, a plurality of polishing units mounted on said table in spaced relation around the periphery thereof, means for rotating said table for moving each unit past an operators station, clamp means on each unit for holding a work piece. abrasive means on each unit operable on the work piece for polishing the same, spring urged pads on either side of said abrasive means pressing said abrasive means against said work piece, means for reciprocating the work piece between said pads, means for reciprocating said pads in a direction substantially normal to the direction of reciprocation of said work piece, and means at the operators station for releasing the grip of said clamp means for moving said abrasive means over said 'pads and for retracting said pads from pressing contact with said abrasive means. v

6. A polishing machine comprising a rotatable table, a. plurality of polishing units mounted in spaced relation around the peripheral edge of said table, power means for rotating said table to move each unit toward and away from an operators station, clamp means on each of said units for holding a'work piece, abrasive means on each unit for polishing said work piece as the table rotates, and means for automatically releasing said clamp means as the unit approaches the operators station.

7. A polishing machine comprising a support structure, polishing members mounted in opposed relation on said structure, a housing slidably mounted on said structure, a clamp disposed at one end of said housing for movement therewith having jaw members holding a workpiece between said polishing members, a rod journaled in said housing having an end portion engaging said jaw members to maintain them in gripping relation on said workpiece, a lever journaled in said housing having an inner end engaging said rod, and an outer end projecting from the side of the housing, means for reciprocating said clamp on said support structure, a bar pivotally mounted on said support structure and extending longitudinally of said housing with a portion disposed under the outer end of Said levers for every position of said reciprocating housing, and means for periodically pivoting said bar to trip said lever and moving said rod to release the grip of said jaws.

8. In a polishing machine, a support structure, a housing mounted for reciprocation on said structure, a pair of jaws pivotally mounted at one end of said housing, a rod journaled in said housing having a tapered end portion in wedging engagement between said jaws for pivoting them into gripping engagement around a work piece, a lever journaled in said housing having one end associated with said rod for moving it longitudinally of said housing and having the other end projecting outwardly of said housing,

a bar pivotally mounted on said support structure below said outwardly projecting end of said lever, and a rock shaft connected to said bar for pivoting the same to trip said lever whereby said rod is moved longitudinally in said housing out of wedging engagement with said jaws.

9. A polishing machine comprising a support structure, polishing members mounted in opposed relation on said structure, a. clamp slidably mounted on said structure having law members holding a workpiece between said polishing members, spring means urging said polishing members toward each other and into contact with opposite sides of said workpiece, means for reciprocating said polishing members, means for reciprocating said clamp on said support structure to move the workpiece between said polishing members, and means for relieving the pressure of said spring means on said polishing members after a predetermined polishing period.

10. A polishing machine comprising a support structure, polishing members mounted in opposed relation on said support structure, s. clamp slidably mounted on said structure having jaw members holding a workpiece between said polishing members, spring means urging said polishing members toward each other and against opposite sides of the workpiece, means for reciprocating said clamp on said structure, each of said polishing means including a pad and an abrasive belt disposed over said pads, means for reciprocating said clamp on said support structure, a. linkage connected to each of said pads for moving the pad away from the opposed pad against the action of said spring means, and means for periodically actuating said linkage.

11. In a polishing machine, 9, support structure, housings mounted in opposed relation on said structure, a member slidably disposed in each housing, a polishing pad mounted on the end of each member confronting a pad on the opposed member, a lever connected to each member for reciprocating the same in the associated housing, a rock shaft operable on each of said levers to effect reciprocation of said members, and means for periodically oscillating said rock shaft.

12. A polishing machine comprising a support structure. a pair of abrasive belts disposed in opposed relation on said structure, a work carrying member having clamping means for holding a workpiece between said belts, pressure means for moving the abrasive surfaces of said belts against the opposite faces of said workpiece at a polishing station, means for reciprocating said work carrying member on said structure to move said workpiece between said belts, and means for releasing said pressure means from said belts. releasing the grip of said clamping means on said work-piece and indexing said belts after a predetermined polishing period to move a new abrasive surface on each of said belts to the polishing station.

13. A polishing machine comprising a support structure, a pair of abrasive polishing members mounted on said structure in opposed relation, each polishing member including an abrasive belt stretched between a supply spool and a take-up spool. a clamp slidably mounted on said structure having jaw' members holding said workpiece between said polishing belts at a polishing station, means for reciprocating said clamp, an idler roller having a friction surface in driving engagement with said take-up spool, a ratchet mechanism mounted on said structure in driving engagement with said idler roller, and means for automatically indexing said ratchet member to move a new abrasive surface of said belt-to said polishing station after a predetermined polishing period.

14. In a polishing machine, a support structure, a polishing member mounted on said support structure including an abrasive belt stretched between a supply spool and a take-up spool, means for reciprocating a workpiece over said belt, an idler roller having a friction surface engaging said take up spool for rotating the same, a ratchet mechanism for periodically indexing said idler roller, and a rock shaft connected to said ratchet mechanism and means for periodically oscillating said rock shaft.

15. A polishing machine comprising a support structure, -polishing members mounted in opposed relation on said structure, a clamp mounted on said structure having jaw members holding a workpiece between said polishing members,

means urging said polishing members toward each other and into contact with opposite sides of said workpiece, means for actuating said clamp structure to reciprocate said work-piece between said polishing members, and means for simultaneously reciprocating saidv polishing members over said reciprocating workpiece.

16. A polishing machine comprising a support structure, a pair of abrasive belts disposed in close confronting relation on said support struc-- ture, a work holder arranged to hold a workpiece between said belts in contact therewith, means for reciprocating said work holder to cause said workpiece to be polished by said belt, and means for reciprocating said belts in a direction substantially normal to the direction of movement of said workpiece.

17. A machine for polishing a workpiece comprising a support structure, a work carrying member reciprocal on said structure, pads disposed on opposite sides of said workpiece and pressing thereagainst, abrasive belts disposed over said pads, means for reciprocating the workpiece in said work carrying member between said pads, and means for moving said pads transversely of said workpiece as said work is reciprocated therebetween.

18. A polishing machine comprising a support structure, polishing members mounted in opposed relation on said structure, a clamp slidably mounted on said support structure having jaw members holding a workpiece between said polishing members, means urging said polishing members toward each other andagainst opposite sides of said workpiece, means for reciprocating said polishing members and means for reciprocating said clamp on said structure to move the workpiece between said polishing members.

19. A polishing machine comprising a support structure, spaced polishing members secured on said structure, a carriage slidably mounted in ways on said support structure, a clamp secured to said carriage` having jaw members holding a workpiece between said polishing members, spring means urging said polishing members against opposite sides of said workpiece, means for reciprocating said carriage to move said workpiece between said polishing members including a cross head adjustably mounted in said carriage, a connecting rod pivotally secured to said cross head, a crank arm pivotally connected to said connecting rod, a crank wayv adjustably receiving said crank arm, and a power driven shaft connected to said crank way for rotating the same, adjustment of said cross head being effective to vary the starting point of the stroke of the cross head and adjustment of the crank arm in the crankway being effective to regulate the length of stroke.

20. A polishing machine comprising a support structure, polishing members mounted in opposed relation on said structure, a clamp mounted on said structure having jaw members holding a workpiece between said polishing members, means for r;ciprocating said clamp to move said workpiece between said polishing members, spring means urging said polishing members toward each other and into contact with the opposite sides of said workpiece, and means for reciprocating said polishing members over said workpiece, said means including a pair of housings mounted in spaced opposed relation on said support structure, each housing having a central bore, a cylindrical member slidably mounted in the bore of eachhousing, a pad secured to the end of each cylindrical member movable. longitudinally with said member and transversely relative to said member, each of said cylindrical members having a longitudinal slot therein, a lever pivotally mounted in each slot having an end pivotally secured to the associated pad, and means for oscillating said levers to reciprocate said pads transversely of said cylindrical members and across said workpiece.

21. In a polishing machine, a support structure, a pair of housings mounted in spaced opposed relation on said support structure, each housing having a central bore, a cylindrical member slidably mounted in the bore of each housing, each cylindrical member having a slot extending longitudinally in one wall thereof, a pad secured to the end of each cylindrical member in confronting relation to the pad secured on the other cylindrical member, said pads having a slotted connection with said cylindrical member to per- ,mit movement of the pad transversely of the member, a lever pivotally disposed in the slot in each member and secured at one end in pivotal engagement with said pad, a linkage secured to the other end of said lever for pivoting the lever to move the pad transversely of the member, and means for periodically actuating said linkage.

22. A polishing machine comprising a support housing, a member slidably disposed in said housing, a polishing pad mounted on the end of said member, a lever connected to said member for reciprocating the same in said housing, a rock shaft operable on said lever to effect reciprocation of said member, and means for periodically oscillating said rock shaft.

23. In a polishing machine, a support structure, a housing mounted for reciprocation on said structure, a pair of jaws pivotally mounted at one end of said housing, a rod journalled in said housing having a tapered end portion in wedging engagement between said jaws for pivoting them into gripping engagement around a work piece, and a, lever mechanism controlled exteriorly of said housing and operatively connected to said rod to move the rod longitudinally in said housing for wedging engagement with said jaws.

24. A polishing machine comprising a rotatable table, a plurality of polishing units mounted on the table for rotation therewith, means for ro-Y tating said table to carry units toward and away from an operator's station, work-carrying means on each unit, means on' each unit for polishing ananas work held by said work carrying means as the table rotates through a predetermined angular path, and means for automatically opening the work carrying means to release the work at the end of said path and to close the work carrying means for gripping the work at the beginning oi' said path.

25. A polishing machine comprising a rotatable table, a plurality of independently operable polishing unita mounted on said table, work-carrying clamps on each unit, means for rotating said table to move said units consecutively to an operators station, and automatic means controlled by the rotatable table for successively releasing the clamping devices of the units to successively provide the released clamping devices at the operators station.

EMIL DACKOR. EDGAR F. NELBOECK. OITO THIEL.

16 assurances man The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 16,141 McDonough Aug. 11, 1925 678,700 Roper June 18, 1901 1,459,085 Black June 19, 1923 1,490,631 Newkirk et al Apr. 15, 1924 1,905,651 Raule Apr. 25, 1933 2,082,020 Moon June 1, 1937 2,123,171 Hamilton July 12, 1938 2,261,902 Indge Nov. 4, 1941 2,461,948 Whitehead Feb. 15, 1949 

